The Hollywood legend has joined the cast of the hit ITV show as Martha Levinson, the wealthy mother of Lady Grantham - whose American attitude is set to clash with the formidable Dowager Countess, played by Dame Maggie.

Shirley told the Daily Telegraph she thinks one reason the show is so popular is that the period drama offers viewers an escape from the reality of the current recession.

"When times are bad, people like to lose themselves in the sheer glamour of another period: beautiful wardrobes, magnificent meals served in elegant settings.

“It's brilliantly done, great writing and fabulous costumes and all that - and certainly the ambience of that time and age is appealing."

And she is looking forward to working with the British legend.

"Maggie's got nothing to fear from me, and I'm just thrilled at the prospect of working with her. I love her to death."